1. Field of the Invention
The present invention relates to an electronic device to which external terminals consisting of metal terminals are connected, for example.
2. Description of the Related Art
In addition to an ordinary chip component directly surface-mounted on a board or so by itself, a chip component to which an external terminal such as a metal terminal is attached is proposed as an electronic device having a ceramic element body such as a ceramic capacitor. It is reported that an electronic device to which an external terminal is attached relaxes a deformation stress that a chip component receives from a board and has an effect of protecting the chip component from impact or so after the electronic device is mounted. The electronic devices are used in fields requiring durability, reliability, and the like.
In the electronic device with the external terminal, one end of the external terminal is connected to a terminal electrode of the chip component, and the other end is connected to a mounting surface such as a circuit board by solder or so. For example, Patent Document 1 discloses that a metal such as copper and copper alloy is used as the external terminal for reducing an electronic resistance.
When a metal such as copper and copper alloy is used as the external terminal, however, a stress is generated at a solder part after the external terminal is connected to a terminal electrode of a ceramic element body by solder or so, because the metal has a thermal expansion coefficient larger than that of the ceramic element body. Thus, there are problems that a strength at a connection part between the terminal electrode of the ceramic element body and the external terminal is decreased, reliability such as thermal shock resistance deteriorates, and the like.
Patent Document 1: JP 2000-235932 A